Conversion of hydrocarbons



Patented Dec. 25, 1945 UNITED 2,391,481 CONVERSION OF'HYDROCARBONS Robert F. Ruthrufl, Chicago, Ill.,

assignon'by direct and 'mesne assignments, of one-half to The M. W. Kellogg Company,

Jersey City, N. 1., a

corporation of Delaware, and one-half to Process Management Company,

Inc., Wilmington,

Del; a corporation of Delaware No'Drawlng. Applicati Serial No. Claims. (Cl. 196-52) The present invention relates to the conversion of hydrocarbons, and particularly to the conversion of high boiling hydrocarbons to low boiling hydrocarbons by catalysis. More particularly, the invention is directed to the conversion of high boiling hydrocarbon fractions such as reduced crudes, gas oils and the like to low boiling fractions within the gasoline or motor fuel boiling range by vaporizing the high boiling hydrocarbons and passing the vapors at an elevated temperature suitable for cracking in contact with a synthetically prepared complex mixture, 'or

' compound, of silica and alumina.

One of the objects of my invention is the provision of a catalyst for the conversion of high boiling hydrocarbons to low boiling hydrocarbons which may be readily and economically prepared synthetically, and which exhibits a high degree of activity in catalyzing such conversion reactions, particularly the conversion of high boiling hydrocarbons such as reduced crudes and gas oils to motor fuel fractions.

A further object of my invention is the provision of a catalyst for such conversions which may be readily and satisfactorily regenerated by oxidation of the carbonaceous material deposited thereon during the conversion.

Various other objects and features of my invention will be apparent as the description thereof proceeds. I

The synthetic silica-alumina complexes employed pursuant to my invention differ radically in physical structure and chemical compo- I sition from natural-occurring or acid-treated absorbent clays such as Super Filtrol which have been heretofore proposed for use in the catalytic cracking of hydrocarbons. While the exact physical and chemical composition of the synthetic silica-alumina complexes employed is not fully understood and accordingly may best be described by reference to their method of preparation, they. in general, comprise silica gel associated or "activated with alumina in an amount suflicient to impart a high degree of catalytic activity in the conversion of high boiling hydro carbons to motor fuel fractons as compared with the catalytic activity for such reactions of either silica gel or alumina alone.

In the practice of my invention, the high boiling hydrocarbons undergoing treatment arervaporized, and the vapors passed in contact with the catalyst for a time ficient to effect the required conversion,

In my copending application Serial Number 305,473, filed November 21, 1939, I have described and =.claimed processes for they conversion of high boilinghydrocarbons to low boiling hydrocarbons employingia synthetic aluminaeactivated silica gel catalyst produced by the activation of a previously prepared siilca gel by the addition of or and at a temperature sufsolution prepared by on November 21, 1939,

and silica in the conversion of high-boilng hydrocarbons to low boling hydrocarbons is largely dependent upon the maintenance of certain ascertained conditions during their preparation, and that catalysts of such a small degree of activity that they are of no practical interest, or a catalyst exhibiting an exceptionally high degree of activity may be prepared dependent upon the observance of the ascertained conditions. The various features of my invention both in its broad and preferred aspects will be evident from a consideration of specific examples of catalyst preparations and their use in the catalytic conversion of high boiling hydrocarbons as exemplified by a specific charging stock, given in the following:

Example 1 A. Silica component-This was derived from a the addition of 315 cc; of water to 250 cc. of the sodium silicate solution having a density of 1.413 and a SiOa content of 30%.

B. Alumina component.--This was derived from a solution prepared by the addition of 55 grams of aluminum nitrate (AliNOa) 3.91120) to 500 cc. of water.

Solution A was heated to 50 C. and added rapidly to solution B with stirring. The resulting mixture was filtered and then washed by stirring with water and refiltering. The washing and filtering treatment was repeated five times. The washed catalyst was then dried in a drying oven at a temperature of about 212 F.

In the foregoing, the sodium silicate and aluminum nitrate were mixed in quantities corre sponding to a molar ratio of silica to alumina of approximately 23 to 1.

Example 2 a solution prepared by the addition or 315 cc. of water, to 250 cc. of sodium silicate having a specific gravity of 1.413 and a S102 content of 30%.

B. Alumina component-This was derived from a solution prepared by theaddition of 500 cc. of water to grams of aluminum nitrate (Al(NO3)a.9H2O). Solution A was heated to 50 C., stirred and added to solution B at once. The gel immediately formed was allowed to stand over night and filtered and washed the same as described in' the preceding example.

In this example the sodium silicate and aluminum nitrate were mixed in quantities corresponding to a molar ratio of silica to alumina of Example 3 This catalyst was prepared exactly like that in Example 2 above, except that the aluminum nitrate solution was prepared by dissolving 220 grams or aluminum nitrate (Al(NOs)a.9H:O) in 500 cc. of water.

In this example the sodium silicate and aluminum nitrate were mixed in quantities corresponding to a molar ratio of silica to alumina or approximately 6 to 1.

Example 4 Example 5 In accordance with this procedure, an ester of silicic acid such as ethyl-orthosilicate is first partially hydrolyzed, following which an aqueous solution 01 an aluminum salt is added, hydrolysis then being allowed to proceed to completion.

A solution was made by mixing together 750 cc. of ethyl-orthosilicate, 437.5 cc. of ethylalcohol and 14 cc. of water. After standing 24 hours, a solution made by dissolving 208 grams of aluminum nitrate (A1(NO3)3.9H2O) in 127.5 cc. of

water. was added slowly with stirring. The reaction mixture was evaporated to apparent dryness at 125 F., and was then dried further at Example 6 A solution was made by mixing 750 cc. of ethyl-orthosilicate with 437.5 cc. oi ethyl alcohol and 14 cc. of a solution containing 22.2 grams of aluminum sulfate AlzdSO-z) 3.18H2O) per liter. After standing 24 hours, 127.5 co. more of the aluminum sulfate solution were added and the whole was evaporated to apparent dryness at 125 1='., following which the catalyst was further dried at 220 F.

Catalysts prepared in accordance with the above examples were employed pursuant to the invention for the conversion of high boiling hydrocarbons to low boiling hydrocarbons as exemplified by the conversion of a Mid-Continent gas-oil to gasoline, the charging stock and other conditions being substantially similar and on a comparable basis.

The charging stock employed in these runs was a Mid-Continent crude gas oil having an A. P. I. gravity of 35.4. an initial boiling point of 482 F. and an end point of 748 F. The charge was vaporized by heating to about 850 F. and then passed over the catalyst at a rate of 100 cc. of oil per hour per 240 cc. of catalyst. Liquid products were collected over each two-hour period, and a representative gas sample collected over a considerable portion of each period. Liquid products were subjected to A. S. T. M. distillation, and the gas sample analyzed by low temperature fractionation. In order to have the results on a comparable basis, the properties of the liquid products were calculated, assuming that all butanes and higher boiling constituents of the gases were incorporated in the liquid products.

The relative efliciency, for the production of gasoline, of catalysts prepared in accordance with Examples 1-4, inclusive, and their composition as shown by analysis, is shown by appended Table 1.

The run in which an alumina-activated catalyst prepared in accordance with Exampl 5 was employed, showed a gasoline production of 32.7% for the first two-hour peri d of the run, and then a drop in efficiency to a fairly constant value of about 7-8% over the remaining eighthour period of the run.

The run in which an alumina-activated catalyst prepared in accordance with Example 6 was employed, showed a low rate of gasoline production varying from 2.5 to 1.4% over the entire run of eight hours. The low rate of catalytic activity in this particular instance was due to the insuflicient quantity of aluminum salt employed in the activation treatment, this quantity being much less than that employed in Example 5.

The variations in activity of catalysts prepared in accordance with Examples 14, inclusive, are attributed to differences in composition and structure of the final catalyst arising out of the amount of aluminum nitrate employed and the extent of removal of sodium compounds. In the more active catalyst preparations numbered 3 and 4, aluminum nitrate was employed in an amount sufficient to provide a quantity of acid by hydrolysis in excess of that required to neutralize the sodium silicate with a resultant formation of the gel in an acid medium.

Although the amount of aluminum nitrate employed in the preparation of catalyst No. 3 was 66% that employed for catalyst No. 4, it is to be noted that the composition and activity of these two catalysts are substantially the same. In the case of catalyst No. 4, the aluminum nitrate in excess of that employed in the preparation of No. 3 self-evidently stayed in solution and was removed in the wash water, thereby serving no useful purpose. Accordingly in the preparation of catalysts in accordanc with my invention, the aluminum salt is preferably added in an amount suilicient to neutralize the alkalinity of sodium silicate but below that amount at which further addition of the aluminum salt causes no increase in the alumina content of the product. A further feature of the preferred method of preparation is the substantially complete removal 01' solubles. particularly sodium compounds by thorough washing of the catalyst. The complete removal of sodium compounds is apparently facilitated by the preparation of the catalyst in an acid medium as in the case of catalysts Nos. 3 and 4.

It is evident from a consideration of catalysts Nos. 1-4. inclusive, that it is possible to incorporate only a certain maximum amount of alumine in the synthetic catalysts prepared in accordance with these examples. Experiments have shown that this maximum quantity is controlled by the amount of sodium oxide present in the original sodium. silicate used. Less than this maximum amount of alumina can be obtained in conjunction with an active catalyst by a variety of methods. For example, catalysts prepared in accord with the teachings of catalyst 1 or catalyst 2 may, after precipitation, be soaked in or washed with dilute acid in order to convert unreacted sodium silicate into silicic acid with the elimination of sodium as a salt of the acid employed, following which any residual solubles are removed by a water wash.. Or, as a substitute for this method, sodium silicates of differing sodium oxide gasoline boiling range. The application of my aluminum nitrate and a solution of ethyl orthoasomai 3 silica ratios may be used. when these are tre'at- W t I cl im is:

ed with sufficient aluminum salt to'give a neutral 1- A p o ess of converti hi h boi i hyd or slightly acid final reaction mixture, precipitates 8 to l w i i hy b n W thin h of variable silica-alumina ratios, in proportion to a l oi i g range which compris p the silica-sodium oxide ratio of the particular 50- 5. ing a gas oil and passing the vapors for a time dium silicate used, are obtained. Or by another and at a temperature suitable for the required modification of my invention, both aluminum salt conversion in contact with a catalyst made by and an acid-is added to the sodium silicate, the add n a hydro yza le salt of aluminum and an total acidity of the two added components being acid to sodium silicate, the tQ l i i y f he suflicient to neutralize the silicate. By this ex- 0 s lt and acid b in sufflcient to n utralize th pedient the quantity or aluminum salt may be resodium silicate, and washing the resulting preduced to any desired quantity. In general, it has cipitate substantially free of soluble material.

been found desirable to employ a minor and rela- 2. A process of converting high boiling hydrotively small amount of alumina relative to the carbons to low boiling hydrocarbons within the silica gel component, i. e. 20% or less. gasoline boiling range which comprises vapor- It will be appreciated that various hydrolyzable izing a gas oil and passing the vapors for a time aluminum salts other than those specified in the and at {a temperature suitable for the required preceding examples maybe used in the practice conversion in contact with a catalyst comprising of the invention, as well as other soluble silicates a precipitated aluminumv silicate, substantially such as potassium silicate. free of soluble material, in which the molar ratio It is to be understood that the particular chargof SiO: to A120: is approximately 10-12 to 1. ing stock and process conditions given above 3. Aprocess for converting high boiling hydromerely exemplify the application of my invention, carbons to, low boiling hydrocarbons which com- I and are susceptible of wide variation. My process prises vaporizing the high boiling hydrocarbons is particularly well exemplified by the treatment 5 and passing the vapors for a time and at a temof heavy boiling hydrocarbon Iractions such as perature suitable for the required conversionin gas oil to produce motor fuels boiling within the contact with a catalyst made by the mixing of invention inthis connection is characterized by silicate to eifect precipitation of an aluminum the production of relatively'high yields of gaso- 3o silicate. I

line. and also a gasoline of relatively high anti- 4. A process for producing a silicavalumina knock quality as compared with gasoline made composite which comprises mixing a solution of by conventional thermal cracking methods. an organic silicon compound with an aluminum salt solution, co-precipitating silica gel and Table 1 t alumina gel from the mixed solutions, and recovering the resultant composite gel.

, '5. A process for, converting a hydrocarbon oil Anal is 1 n1 I out aga egi'ent b teat, 223? Percent boiling substantially entirely above the gasoline 1m 0,, 1 m' ga boiling range to lower boiling gasoline constithours 40 uents which comprises contacting said high boilno A N o i i ing hydrocarbon oil at a temperature suitable for the required conversion with a catalyst comprisz M 5 3 ing a silica-alumina complex, substantially free 12.1 85.1 13.1 4.8 121.1 14.0 6 1 85.4 14.3 as 1am see from soluble material, in which the molar ratio W 45 of sin: to A: is approximately 10-12 to 1.

ROBERT F. RUTHR-UFF. 

